1. Field of the Invention
The present invention relates to an optical disk recording and reproducing apparatus for recording a signal on a disk using light beams emitted from a laser diode built in an optical pickup and for reproducing a signal recorded on the disk using the light beams.
2. Description of the Related Art
Disk players which use an optical pickup to read out signals recorded on a disk have become very popular. In more recent years, optical disk recording and reproducing apparatuses have become commercialized. In addition to a playback function, such an optical disk recording and reproducing apparatus can record a signal on a disk using light beams emitted from a laser diode built into an optical pickup.
A typical optical disk recording and reproducing apparatus is constructed so that the operation of recording a signal is performed in accordance with a recording instruction supplied from a computer system serving as a host device. In the recording operation, a signal to be recorded on the disk is temporarily stored in a buffer RAM and the signal stored in the buffer RAM is read out to perform the signal recording operation.
As long as the operation of recording a signal on the disk is performed normally, the operation of writing a recording signal generated from the computer system in the buffer RAM, the operation of reading the signal from the buffer RAM, and the operation of recording the read-out signal on the disk are performed in accordance with the amount of recording signal data and the recording situation in the disk.
During the signal recording operation, when the amount of recording signal data stored in the buffer RAM is insufficient, the operation of recording signals on the disk cannot be performed, namely, a situation called buffer underrun occurs. As a method for solving the above problem, the following technology is developed. That is, when the amount of recording signal data stored in the buffer RAM passes below a predetermined value, referred to as an interruption set value, the recording operation in the disk is temporarily halted, and, when the amount of recording signal data stored in the buffer RAM is again larger than the predetermined value, now a resumption set value, the recording operation in the disk is resumed.
As a method for dealing with the problem regarding buffer underrun, there is a method for performing the operation of interrupting recording and the operation of resuming the recording. In the recording resuming operation, a signal recorded on the disk before interruption of the recording is reproduced, a reference signal included in the reproduced signal is synchronized with a recording reference signal, and the recording operation is resumed upon synchronization. However, the recording operation is not resumed immediately after the synchronization of the reference signal with the recording reference signal. When the number of frames constituting the recording signal reaches a predetermined number after the synchronization, the recording operation is resumed.
The technology of performing the above-mentioned recording interrupting and resuming operation is developed in order to prevent buffer underrun. It is considered that the technology is utilized in situations wherein the recording operation is unexpectedly interrupted due to an applied external force.
In the recording interrupting and resuming operation which is performed in order to prevent the buffer underrun, a position where the recording is interrupted can be set so as to be suitable for performing the recording resuming operation, namely, so as to be suitable for continuing signals to be recorded by the recording interrupting and resuming operation. However, when the recording operation is interrupted due to an applied external force, a position where the recording is interrupted cannot be set arbitrarily. Accordingly, it is difficult to maintain the continuity of recorded signals.